Methods of forming light emitting devices having current reducing structures

ABSTRACT

A light emitting device includes a p-type semiconductor layer, an n-type semiconductor layer, and an active region between the n-type semiconductor layer and the p-type semiconductor layer. A non-transparent feature, such as a wire bond pad, is on the p-type semiconductor layer or on the n-type semiconductor layer opposite the p-type semiconductor layer, and a reduced conductivity region is in the p-type semiconductor layer or the n-type semiconductor layer and is aligned with the non-transparent feature. The reduced conductivity region may extend from a surface of the p-type semiconductor layer opposite the n-type semiconductor layer towards the active region and/or from a surface of the n-type semiconductor layer opposite the p-type semiconductor layer towards the active region.

RELATED APPLICATION

The present application is a divisional of U.S. patent application Ser.No. 11/715,687 filed Mar. 8, 2007 now U.S. Pat. No. 7,795,623 which is acontinuation-in-part of U.S. patent application Ser. No. 10/881,814,filed on Jun. 30, 2004 now abandoned, the disclosure of which is herebyincorporated by reference herein as if set forth in its entirety.

FIELD OF THE INVENTION

This invention relates to semiconductor light emitting devices andfabricating methods therefor.

BACKGROUND

Semiconductor light emitting devices, such as Light Emitting Diodes(LEDs) or laser diodes, are widely used for many applications. As iswell known to those having skill in the art, a semiconductor lightemitting device includes a semiconductor light emitting element havingone or more semiconductor layers that are configured to emit coherentand/or incoherent light upon energization thereof. As is well known tothose having skill in the art, a light emitting diode or laser diode,generally includes a diode region on a microelectronic substrate. Themicroelectronic substrate may be, for example, gallium arsenide, galliumphosphide, alloys thereof, silicon carbide and/or sapphire. Continueddevelopments in LEDs have resulted in highly efficient and mechanicallyrobust light sources that can cover the visible spectrum and beyond.These attributes, coupled with the potentially long service life ofsolid state devices, may enable a variety of new display applications,and may place LEDs in a position to compete with the well entrenchedincandescent and fluorescent lamps.

Much development interest and commercial activity recently has focusedon LEDs that are fabricated in or on silicon carbide, because these LEDscan emit radiation in the blue/green portions of the visible spectrum.See, for example, U.S. Pat. No. 5,416,342 to Edmond et al., entitledBlue Light-Emitting Diode With High External Quantum Efficiency,assigned to the assignee of the present application, the disclosure ofwhich is hereby incorporated herein by reference in its entirety as ifset forth fully herein. There also has been much interest in LEDs thatinclude gallium nitride-based diode regions on silicon carbidesubstrates, because these devices also may emit light with highefficiency.

The efficiency of conventional LEDs may be limited by their inability toemit all of the light that is generated by their active region. When anLED is energized, light emitting from its active region (in alldirections) may be prevented from exiting the LED by, for example, anon-transparent wire bond pad. Typically, in gallium nitride based LEDs,a current spreading contact layer is provided to improve the uniformityof carrier injection across the cross section of the light emittingdevice. Current is injected into the p-side of the LED through the bondpad and the p-type contact. Light generated in an active region of thedevice is proportional to the carrier injection. Thus, a substantiallyuniform photon emission across the active region may result from the useof a current spreading layer, such as a substantially transparent p-typecontact layer. However, a wire bond pad is typically not a transparentstructure and, therefore, photons emitted from the active region of theLED that are incident upon the wire bond pad may be absorbed by the wirebond pad. For example, in some instances approximately 70% of the lightincident on the wire bond pad may be absorbed. Such photon absorptionmay reduce the amount of light that escapes from the LED and maydecrease the efficiency of the LED.

SUMMARY

A light emitting device according to some embodiments of the inventionincludes a p-type semiconductor layer, an n-type semiconductor layer,and an active region between the n-type semiconductor layer and thep-type semiconductor layer. A non-transparent feature is on the p-typesemiconductor layer or on the n-type semiconductor layer opposite thep-type semiconductor layer, and a reduced conductivity region is in thep-type semiconductor layer and is aligned with the non-transparentfeature. The reduced conductivity region extends from a surface of thep-type semiconductor layer opposite the n-type semiconductor layertowards the active region. The non-transparent region may include a wirebond pad, a passivation region, and/or a current spreading finger.

The light emitting device may further include a substrate includingfirst and second opposing surfaces, and the n-type semiconductor may beon the first surface of the substrate and the wire bond pad may be onthe second surface of the substrate opposite the n-type semiconductorlayer.

The light emitting device may further include a metal stack on thesurface of the p-type semiconductor layer. The metal stack may includean ohmic layer directly on the p-type semiconductor layer, a reflectivelayer on the ohmic layer, and a bonding layer on the reflective layer.The light emitting device may further include a barrier layer betweenthe reflective layer and the bonding layer.

The reduced conductivity region may extend from the surface of thep-type semiconductor layer to/into/through the active region. Thereduced conductivity region may extend through the p-type semiconductorlayer, the active region and into or through the n-type semiconductorlayer.

The wire bond pad may be in contact with the reduced conductivityregion, and the light emitting device may further include an ohmiccontact on the n-type semiconductor layer adjacent and in electricalcontact with the wire bond pad.

The active region may include a Group III-nitride based active region.The reduced conductivity region may include an insulating region and/ora region that is not non-transparent. In some embodiments, the reducedconductivity region may include an implanted region. The reducedconductivity region may correspond to a region of damage at an interfacebetween the metal stack and the p-type semiconductor layer. The regionof damage may include a wet or dry etched region of the p-typesemiconductor layer, a region of the p-type semiconductor layer exposedto a high energy plasma, a region of the p-type semiconductor layerexposed to H₂ and/or a region of the p-type semiconductor layer exposedto a high energy laser.

A light emitting device according to further embodiments of theinvention includes a p-type semiconductor layer, an n-type semiconductorlayer, and an active region between the n-type semiconductor layer andthe p-type semiconductor layer. The device includes a non-transparentfeature on the n-type semiconductor layer opposite the p-typesemiconductor layer, and a metal contact on a surface of the p-typesemiconductor layer opposite the n-type semiconductor layer. The metalcontact forms on ohmic contact to the p-type semiconductor layer in aregion other than a reduced conductivity area of the surface of thep-type semiconductor layer that is aligned with the non-transparentfeature. The non-transparent region may include a wire bond pad, apassivation region, and/or a current spreading finger

The light emitting device may further include a reduced conductivityregion in the p-type semiconductor layer and aligned with thenon-transparent feature and the reduced conductivity area, and thereduced conductivity region may extend from the surface of the p-typesemiconductor layer towards the active region.

The light emitting device may further include a reduced conductivityregion in the n-type semiconductor layer and aligned with thenon-transparent feature, the reduced conductivity region extending froma surface of the n-type semiconductor layer opposite the p-typesemiconductor layer towards the active region.

The light emitting device may further include a non-ohmic contact on thesurface of the p-type semiconductor layer. The non-ohmic contact mayinclude a metal that does not form an ohmic contact with the p-typesemiconductor layer and/or an insulator on the surface of the p-typesemiconductor layer.

A light emitting device according to further embodiments of theinvention includes a p-type semiconductor layer, an n-type semiconductorlayer, and an active region between the n-type semiconductor layer andthe p-type semiconductor layer. The device further includes a wire bondpad on the n-type semiconductor layer opposite the p-type semiconductorlayer, and a reduced conductivity region in the n-type semiconductorlayer and aligned with the wire bond pad. The reduced conductivityregion extends from a surface of the n-type semiconductor layer oppositethe p-type semiconductor layer towards the active region. The devicefurther includes an ohmic contact on the n-type semiconductor layeradjacent and in electrical contact with the wire bond pad.

The light emitting device may further include a metal stack on a surfaceof the p-type semiconductor layer opposite the n-type semiconductorlayer. The metal stack may include an ohmic layer directly on the p-typesemiconductor layer, a reflective layer on the ohmic layer, and abonding layer on the reflective layer.

The reduced conductivity region may include a first reduced conductivityregion, and the light emitting device may further include a secondreduced conductivity region in the p-type semiconductor layer andaligned with the wire bond pad. The second reduced conductivity regionmay extend from a surface of the p-type semiconductor layer opposite then-type semiconductor layer towards the active region.

The light emitting device may further include a metal contact on asurface of the p-type semiconductor layer opposite the n-typesemiconductor layer. The metal contact forms on ohmic contact to thep-type semiconductor layer in a region other than a reduced conductivityarea of the surface of the p-type semiconductor layer that is alignedwith the wire bond pad.

Methods according to some embodiments of the invention include forming ap-type semiconductor layer, an n-type semiconductor layer, and an activeregion between the n-type semiconductor layer and the p-typesemiconductor layer, forming a non-transparent feature on the n-typesemiconductor layer opposite the p-type semiconductor layer, and forminga reduced conductivity region in the p-type semiconductor layer andaligned with the non-transparent feature. The reduced conductivityregion extends from a surface of the p-type semiconductor layer oppositethe n-type semiconductor layer towards the active region.

Methods of forming a light emitting device according to furtherembodiments of the invention include forming a p-type semiconductorlayer, an n-type semiconductor layer, and an active region between then-type semiconductor layer and the p-type semiconductor layer, forming awire bond pad on the n-type semiconductor layer opposite the p-typesemiconductor layer, and forming a metal contact on a surface of thep-type semiconductor layer opposite the n-type semiconductor layer. Themetal contact forms on ohmic contact to the p-type semiconductor layerin a region other than a reduced conductivity area of the surface of thep-type semiconductor layer that is aligned with the wire bond pad.

A light emitting device according to further embodiments of theinvention includes a p-type semiconductor layer, an n-type semiconductorlayer, and an active region between the n-type semiconductor layer andthe p-type semiconductor layer. A bond pad is on the p-typesemiconductor layer opposite the n-type semiconductor layer, and areduced conductivity region is in the p-type semiconductor layer andaligned with the bond pad. The reduced conductivity region extends froma surface of the p-type semiconductor layer opposite the n-typesemiconductor layer towards the active region.

The light emitting device may further include a reflector between thebondpad and the p-type semiconductor layer and/or a current spreadingfinger on the p-type semiconductor layer, and the reduced conductivityregion may further be aligned with the current spreading finger.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view illustrating semiconductor lightemitting devices having a current blocking structure according to someembodiments of the present invention.

FIGS. 2A and 2B are cross-sectional views illustrating fabrication ofsemiconductor devices according to some embodiments of the presentinvention.

FIGS. 3 through 11 are cross-sectional views of light emitting devicesaccording to further embodiments of the present invention.

FIGS. 12 and 13 are perspective views of light emitting devicesaccording to some embodiments of the present invention.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

The present invention now will be described more fully hereinafter withreference to the accompanying drawings, in which embodiments of theinvention are shown. However, this invention should not be construed aslimited to the embodiments set forth herein. Rather, these embodimentsare provided so that this disclosure will be thorough and complete, andwill fully convey the scope of the invention to those skilled in theart. In the drawings, the thickness of layers and regions areexaggerated for clarity. Like numbers refer to like elements throughout.As used herein the term “and/or” includes any and all combinations ofone or more of the associated listed items.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of the invention. Asused herein, the singular forms “a”, “an” and “the” are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. It will be further understood that the terms “comprises”and/or “comprising,” when used in this specification, specify thepresence of stated features, integers, steps, operations, elements,and/or components, but do not preclude the presence or addition of oneor more other features, integers, steps, operations, elements,components, and/or groups thereof.

It will be understood that when an element such as a layer, region orsubstrate is referred to as being “on” or extending “onto” anotherelement, it can be directly on or extend directly onto the other elementor intervening elements may also be present. In contrast, when anelement is referred to as being “directly on” or extending “directlyonto” another element, there are no intervening elements present. Itwill also be understood that when an element is referred to as being“connected” or “coupled” to another element, it can be directlyconnected or coupled to the other element or intervening elements may bepresent. In contrast, when an element is referred to as being “directlyconnected” or “directly coupled” to another element, there are nointervening elements present. Like numbers refer to like elementsthroughout the specification.

It will be understood that, although the terms first, second, etc. maybe used herein to describe various elements, components, regions, layersand/or sections, these elements, components, regions, layers and/orsections should not be limited by these terms. These terms are only usedto distinguish one element, component, region, layer or section fromanother region, layer or section. Thus, a first element, component,region, layer or section discussed below could be termed a secondelement, component, region, layer or section without departing from theteachings of the present invention.

Furthermore, relative terms, such as “lower” or “bottom” and “upper” or“top,” may be used herein to describe one element's relationship toanother elements as illustrated in the Figures. It will be understoodthat relative terms are intended to encompass different orientations ofthe device in addition to the orientation depicted in the Figures. Forexample, if the device in the Figures is turned over, elements describedas being on the “lower” side of other elements would then be oriented on“upper” sides of the other elements. The exemplary term “lower”, cantherefore, encompasses both an orientation of “lower” and “upper,”depending of the particular orientation of the figure. Similarly, if thedevice in one of the figures is turned over, elements described as“below” or “beneath” other elements would then be oriented “above” theother elements. The exemplary terms “below” or “beneath” can, therefore,encompass both an orientation of above and below.

Embodiments of the present invention are described herein with referenceto cross-section illustrations that are schematic illustrations ofidealized embodiments of the present invention. As such, variations fromthe shapes of the illustrations as a result, for example, ofmanufacturing techniques and/or tolerances, are to be expected. Thus,embodiments of the present invention should not be construed as limitedto the particular shapes of regions illustrated herein but are toinclude deviations in shapes that result, for example, frommanufacturing. For example, an etched region illustrated or described asa rectangle will, typically, have rounded or curved features. Thus, theregions illustrated in the figures are schematic in nature and theirshapes are not intended to illustrate the precise shape of a region of adevice and are not intended to limit the scope of the present invention.

Unless otherwise defined, all terms (including technical and scientificterms) used herein have the same meaning as commonly understood by oneof ordinary skill in the art to which this invention belongs. It will befurther understood that terms, such as those defined in commonly useddictionaries, should be interpreted as having a meaning that isconsistent with their meaning in the context of this specification andthe relevant art and will not be interpreted in an idealized or overlyformal sense unless expressly so defined herein.

It will also be appreciated by those of skill in the art that referencesto a structure or feature that is disposed “adjacent” another featuremay have portions that overlap or underlie the adjacent feature.

Although various embodiments of LEDs disclosed herein include asubstrate, it will be understood by those skilled in the art that thecrystalline epitaxial growth substrate on which the epitaxial layerscomprising an LED are grown may be removed, and the freestandingepitaxial layers may be mounted on a substitute carrier substrate orsubmount which may have better thermal, electrical, structural and/oroptical characteristics than the original substrate. The inventiondescribed herein is not limited to structures having crystallineepitaxial growth substrates and may be utilized in connection withstructures in which the epitaxial layers have been removed from theiroriginal growth substrates and bonded to substitute carrier substrates.

Some embodiments of the present invention may provide for improvedefficacy of a light emitting device by reducing and/or preventingcurrent flow in an active region of the device in a region beneath awire bond pad or other non-transparent structure. Thus, some embodimentsof the present invention may provide light emitting devices and methodsof fabricating light emitting devices having a current blockingmechanism below the wire bond pad. By reducing and/or preventing currentfrom being injected directly beneath the wire bond pad, the current maybe more likely to be converted to photon emission in areas of the devicenot under the wire bond pad. Thus, there may be a reduced probability oflight being absorbed by the wire bond pad. In some embodiments of thepresent invention, an increase in efficiency of a light emitting deviceaccording to some embodiments of the present invention may beproportional to the size of the wire bond pad.

Embodiments of the present invention may be particularly well suited foruse in nitride-based light emitting devices such as Group III-nitridebased devices. As used herein, the term “Group III nitride” refers tothose semiconducting compounds formed between nitrogen and the elementsin Group III of the periodic table, usually aluminum (Al), gallium (Ga),and/or indium (In). The term also refers to ternary and quaternarycompounds such as AlGaN and AlInGaN. As is well understood by those inthis art, the Group III elements can combine with nitrogen to formbinary (e.g., GaN), ternary (e.g., AlGaN, AlInN), and quaternary (e.g.,AlInGaN) compounds. These compounds all have empirical formulas in whichone mole of nitrogen is combined with a total of one mole of the GroupIII elements. Accordingly, formulas such as Al_(x)Ga_(1-x)N where 0≦x≦1are often used to describe them. However, while embodiments of thepresent invention are described herein with reference to GroupIII-nitride based light emitting devices, such as gallium nitride basedlight emitting devices, certain embodiments of the present invention maybe suitable for use in other semiconductor light emitting devices, suchas for example, GaAs and/or GaP based devices.

Light emitting devices according to some embodiments of the presentinvention may include a light emitting diode, laser diode and/or othersemiconductor device which includes one or more semiconductor layers,which may include silicon, silicon carbide, gallium nitride and/or othersemiconductor materials, a substrate which may include sapphire,silicon, silicon carbide and/or other microelectronic substrates, andone or more contact layers which may include metal and/or otherconductive layers. In some embodiments, ultraviolet, blue and/or greenLEDs may be provided. The design and fabrication of semiconductor lightemitting devices are well known to those having skill in the art andneed not be described in detail herein.

For example, light emitting devices according to some embodiments of thepresent invention may include structures such as the galliumnitride-based LED and/or laser structures fabricated on a siliconcarbide substrate such as those devices manufactured and sold by Cree,Inc. of Durham, N.C. The present invention may be suitable for use withLED and/or laser structures that provide active regions such asdescribed in U.S. Pat. Nos. 6,201,262; 6,187,606; 6,120,600; 5,912,477;5,739,554; 5,631,190; 5,604,135; 5,523,589; 5,416,342; 5,393,993;5,338,944; 5,210,051; 5,027,168; 5,027,168; 4,966,862 and/or 4,918,497,the disclosures of which are incorporated herein by reference as if setforth fully herein. Other suitable LED and/or laser structures aredescribed in published U.S. Patent Publication No. US 2003/0006418 A1entitled Group III Nitride Based Light Emitting Diode Structures With aQuantum Well and Superlattice, Group III Nitride Based Quantum WellStructures and Group III Nitride Based Superlattice Structures,published Jan. 9, 2003, as well as published U.S. Patent Publication No.US 2002/0123164 A1 entitled Light Emitting Diodes IncludingModifications for Light Extraction and Manufacturing Methods Therefor.Furthermore, phosphor coated LEDs, such as those described in U.S.application Ser. No. 10/659,241, entitled Phosphor-Coated Light EmittingDiodes Including Tapered Sidewalls and Fabrication Methods Therefor,filed Sep. 9, 2003, the disclosure of which is incorporated by referenceherein as if set forth fully, may also be suitable for use inembodiments of the present invention. The LEDs and/or lasers may beconfigured to operate such that light emission occurs through thesubstrate. In such embodiments, the substrate may be patterned so as toenhance light output of the devices as is described, for example, in theabove-cited U.S. Patent Publication No. US 2002/0123164 A1. Thesestructures may be modified as described herein to provide blockingstructures according to some embodiments of the present invention.

Thus, for example, embodiments of the present invention may be utilizedwith light emitting devices having bond pads of differing shapes orsizes. The light emitting devices may be on differing substrates, suchas silicon carbide, sapphire, gallium nitride, silicon or othersubstrate suitable substrate for providing Group III-nitride devices.The light emitting devices may be suitable for subsequent singulationand mounting on a suitable carrier. The light emitting devices mayinclude, for example, single quantum well, multi-quantum well and/orbulk active region devices. Some embodiments of the present inventionmay be used with devices utilizing a tunneling contact on the p-side ofthe device.

FIG. 1 is a cross-sectional schematic illustration of a light emittingdevice according to some embodiments of the present invention. As seenin FIG. 1, a substrate 10, such as an n-type silicon carbide substrate,has an optional n-type semiconductor layer 12, such as a gallium nitridebased layer, provided thereon. The n-type semiconductor layer 12 mayinclude multiple layers, for example, buffer layers or the like. In someembodiments of the present invention, the n-type semiconductor layer 12is provided as an AlGaN layer, that may be of uniform or gradientcomposition, and/or a GaN layer. The n-type semiconductor layer 12 maybe doped, for example, with silicon, germanium and/or tellurium.

While described herein with reference to a silicon carbide substrate, insome embodiments of the present invention other substrate materials maybe utilized. For example, a sapphire substrate, GaN or other substratematerial may be utilized. In such a case, the contact 20 may be located,for example, in a recess that contacts the n-type semiconductor layer12, so as to provide a second contact for the device. Otherconfigurations may also be utilized.

An active region 14, such as a single or double heterostructure, quantumwell, multi-quantum well or other such active region may be provided onthe n-type semiconductor layer. As used herein, the term “active region”refers to a region of semiconductor material of a light emitting device,that may be one or more layers and/or portions thereof, where asubstantial portion of the photons emitted by the device when inoperation are generated by carrier recombination. In some embodiments ofthe present invention, the active region refers to a region wheresubstantially all of the photons emitted by the device are generated bycarrier recombination.

Also illustrated in FIG. 1 is an optional p-type semiconductor layer 16.The p-type semiconductor material layer 16 may, for example, be agallium nitride based layer, such as a GaN layer. In particularembodiments of the present invention, the p-type semiconductor layer 16includes magnesium doped GaN. The p-type semiconductor layer 16 mayinclude one or multiple layers and may be of uniform or gradientcomposition. In some embodiments of the present invention, the p-typesemiconductor layer 16 is part of the active region 14.

A first contact metal layer 18 of contact metal that provides an ohmiccontact to the p-type semiconductor material layer 16 is also provided.In some embodiments, the first contact metal layer 18 may function as acurrent spreading layer. In particular embodiments of the presentinvention where the p-type semiconductor material layer 16 is GaN, thefirst contact metal layer 18 may include Pt, indium-tin-oxide (ITO) oranother transparent material that can farm an ohmic contact to p-typeGaN. In certain embodiments of the present invention, the first contactmetal layer 18 is light permeable and in some embodiments issubstantially transparent. In some embodiments, the first contact metallayer 18 may be a relatively thin layer of Pt. For example, the firstcontact metal layer 18 may be a layer of Pt that is about 15 Å thick. Anoptional reflective layer 23 may be provided on the first metal contactlayer 18. A wire bond pad 22 or other light absorbing (or otherwisenon-transparent) feature is provided on the first contact metal layer18. In the embodiments illustrated in FIG. 1, the wire bond pad 22 isprovided on the reflective layer 23, so that the reflective layer 23 isbetween the wire bond pad 22 and the p-type semiconductor material layer16. In some embodiments, a current spreading finger 154A (FIG. 13) maybe on the first contact metal layer 18.

A second contact metal layer 20 of contact metal that provides an ohmiccontact to the n-type semiconductor material is also provided. Thesecond contact metal layer 20 may be provided on a side of the substrate10 opposite the active region 14. As discussed above, in someembodiments of the present invention the second contact metal layer maybe provided on a portion of the n-type semiconductor material layer 12,for example, in a recess or at a base of a mesa including the activeregion. Furthermore, in some embodiments of the present invention, anoptional back-side implant or additional epitaxial layers may beprovided between the substrate 10 and the second contact metal layer 20.

As is further illustrated in FIG. 1, a reduced conductivity region 30 isprovided in the active region 14. The reduced conductivity region 30 maybe positioned beneath light absorbing and/or non-transparent featuresand/or regions of the device. For example, as shown in FIG. 1, thereduced conductivity region 30 may be positioned beneath the wire bondpad 22. A reduced conductivity region 30 may also be positioned beneathother features of the chip, such as passivation regions along an edge ofthe chip, current spreading fingers on a surface of the chip, or otherfeatures or areas of the chip that may tend to absorb light emitted bythe chip.

In some embodiments of the present invention, the reduced conductivityregion 30 extends through the active region 14. As used herein, reducedconductivity refers to a region with reduced current flow over otherportions of the active region. In particular embodiments, the reductionis at least an order of magnitude and in some embodiments, substantiallyall current flow is blocked in the reduced conductivity region.

As noted above, in some embodiments of the present invention the reducedconductivity region 30 extends through the active region 14. In furtherembodiments of the present invention, the reduced conductivity region 30extends from the first contact metal layer 18 to the active region 14.In some embodiments, the reduced conductivity region extends from thefirst contact layer 18 into the active region 14. In some embodiments,the reduced conductivity region extends from the first contact layer 18through the active region 14. The reduced conductivity region 30 mayhave substantially the same shape and/or area as the area of the wirebond pad 22 on the first contact metal layer 18. In some embodiments ofthe present invention, the reduced conductivity region 30 has a slightlylarger area than the wire bond pad 22 while in other embodiments of thepresent invention, the reduced conductivity region 30 has a slightlysmaller area than the wire bond pad 22. In certain embodiments of thepresent invention, the reduced conductivity region 30 does not absorblight or only absorbs a relatively small amount of light. In someembodiments of the present invention, the reduced conductivity region 30is an insulating region.

The reduced conductivity region 30 may reduce and/or prevent currentflow through the active region 14 in the area beneath the wire bond pad22, so that carriers have a tendency to be injected in areas other thanthe reduced conductivity region 30. Thus, the presence of the reducedconductivity region 30 may reduce and/or prevent light generationthrough carrier recombination in this region. While not being bound by aparticular theory of operation, this may be the case because thelikelihood that a photon generated in the portion of the active regionbeneath the wire bond pad 22 is absorbed by the wire bond pad 22 may behigher than if the photon is generated in a portion of the active regionthat is not beneath the wire bond pad 22. By reducing and/or eliminatingthe light generated in the active region beneath the wire bond pad 22,the portion of the light generated by the light emitting device that isabsorbed by the wire bond pad 22 may be reduced. For a given set ofoperating conditions, this reduction in the amount of light absorbed bythe wire bond pad 22 may result in increased light extraction from thelight emitting device as compared to a device operating under the sameconditions where light is generated in the region beneath the wire bondpad 22. Thus, some embodiments of the present invention provide areduced conductivity region 30 that extends into and, in someembodiments, through the active region 14 in the area beneath the wirebond pad 22. This may reduce the likelihood that carriers may spread andbe injected into the active region 14 beneath the wire bond pad 22 and,thereby, result in photon generation in the area beneath the wire bondpad 22.

FIGS. 2A and 2B illustrate operations according to some embodiments ofthe present invention for forming light emitting devices having areduced conductivity region as illustrated in FIG. 1. As seen in FIG.2A, the various layers/regions of the light emitting device arefabricated. The particular operations in the fabrication of the lightemitting device will depend on the structure to be fabricated and aredescribed in the United States patents and/or applications incorporatedby reference above and/or are well known to those of skill in the artand, therefore, need not be repeated herein. FIG. 2A also illustratesformation of a mask 40 having a window 42 corresponding to the regionwhere the wire bond pad 22 is to be formed.

An implant is performed using the mask 40 so as to implant atoms intothe active region 14 in the region of the wire bond pad 22 so as to formthe reduced conductivity region 30 as seen in FIG. 2B. Such an implantmay, for example, be a nitrogen implant. For example, for a galliumnitride based device, implant conditions of 60 keV, 2×10¹³ cm⁻³ N₂ mayproduce a non-absorbing and insulating region in Mg doped GaN. Theparticular implant energy and/or atoms may depend on the structure inwhich the reduced conductivity region 30 is formed.

As seen in FIG. 2B, after implantation, the wire bond pad 22 may beformed in the window 42. In some embodiments, a reflective layer 23 maybe formed in the window 42 prior to formation of the wire bond pad 22.Thus, in some embodiments of the present invention, the wire bond pad 22(and possibly the reflective layer 23) and the reduced conductivityregion 30 may be self-aligned. The wire bond pad 22 may be formed, forexample, by forming a layer or layers of metal and then planarizing thelayers to provide the wire bond pad 22. The mask 40 may subsequently beremoved. Optionally, the mask 40 may be made of an insulating material,such as SiO₂ and/or MN, and may remain on the device as, for example, apassivation layer, or be removed.

FIG. 3 illustrates light emitting devices according to furtherembodiments of the present invention. In FIG. 3, the first contact metallayer 18 includes a first portion 55 in contact with the p-typesemiconductor material layer 16 that provides an ohmic contact to thep-type semiconductor material layer 16 and a second portion 57 incontact with the p-type semiconductor material layer 16 that does notform an ohmic contact to the p-type semiconductor material layer 16. Asused herein the term “ohmic contact” refers to a contact with a specificcontact resistivity of less than about 10 e −03 ohm-cm² and, in someembodiments less than about 10 e −04 ohm-cm². Thus, a contact that isrectifying or that has a high specific contact resistivity, for example,a specific contact resistivity of greater than about 10 e −03 ohm-cm²,is not an ohmic contact as that term is used herein.

The second portion 57 corresponds to the location of the wire bond pad22. By not forming an ohmic contact, current injection into the p-typesemiconductor material layer 16 in the portion 57 may be reduced and/orprevented. The portion 57 that does not form an ohmic contact may beprovided by damaging the p-type semiconductor layer 16 and/or the firstcontact metal layer 18 in the region 50 beneath the wire bond pad 22.

For example, in gallium nitride based devices, the quality of theinterface between the contact metal and the p-type semiconductormaterial may determine the quality of the resulting ohmic contact. Thus,for example, the p-type semiconductor material layer 16 in the region 50may be exposed to a high energy plasma, such as Ar, to reduce p-typeconductivity before formation of the first contact metal layer 18. Also,the p-type semiconductor material layer 16 and the first contact metallayer 18 in the region 50 may be exposed to a high energy plasma todamage the metal/GaN interface after formation of the first contactmetal layer 18. The p-type semiconductor material 16 in the region 50may be exposed to a H₂ while protecting the other regions of the p-typesemiconductor material layer 16 before formation of the first contactmetal layer 18. The p-type semiconductor material 16 in the region 50may be wet or dry etched while protecting the other regions of thep-type semiconductor material layer 16 before formation of the firstcontact metal layer 18. Also, the p-type semiconductor material layer 16in the region 50 may be exposed to a high energy laser while protectingthe other regions of the p-type semiconductor material 16 beforeformation of the first contact metal layer 18.

Such selective damaging of the p-type semiconductor material layer 16and/or metal layer 18 may be provided, for example, using a mask such asdescribed above with reference to FIGS. 2A and 2B and/or by controllinga laser. The particular conditions utilized may vary depending on theprocedure utilized and the composition of the p-type semiconductormaterial layer 16 and/or the first metal contact layer 18.

FIG. 4A illustrates light emitting devices according to furtherembodiments of the present invention. In FIG. 4A, a Schottky contact 60is provided on the p-type semiconductor material layer 16 and the firstcontact metal layer 18′ formed on the p-type semiconductor materiallayer 16 and the Schottky contact 60. The wire bond pad 22 is providedon the portion of the first contact metal layer 18′ on the Schottkycontact 60. By forming a Schottky contact 60, current injection into thep-type semiconductor material layer 16 from the first contact metallayer 18′ may be reduced and/or prevented in the region of the Schottkycontact 60.

Alternatively, as shown in FIG. 4B, a rectifying junction may beprovided in the region below the wire bond pad 22. The rectifyingjunction may be provided, for example, by implanting the p-typesemiconductor material layer 16 with n-type ions so as to convert theregion 70 beneath the wire bond pad 22 to n-type semiconductor material.Such an implant may, for example, be carried out using a mask such asdiscussed above with reference to FIGS. 2A and 2B. Alternatively, aregion of n-type material could be formed where the Schottky contact 60is illustrated in FIG. 4A and the first contact metal 18′ could beformed on the region of n-type semiconductor material and the p-typesemiconductor material layer 16.

Referring to FIG. 5, some embodiments of the invention provide a lightemitting device 100A including a substrate 110 on which an n-typesemiconductor layer 112, an active region 114 and a p-type semiconductorlayer 116 are formed. The semiconductor substrate 110 may include aconductive silicon carbide substrate, for example, and the n-typesemiconductor layer 112, the active region 114 and the p-typesemiconductor layer 116 may include group III-nitride basedsemiconductor layers. The light emitting device 100A further includes areduced conductivity region 130 in the p-type semiconductor layer 116.As seen in FIG. 5, the substrate 110 may include shaped sidewalls 111that may increase the efficiency of light extraction from the device100A by changing the angle at which light generated in the active region114 strikes the sidewalls of the device 100A. In the structureillustrated in FIG. 5, the reduced conductivity region 130 may belocated a distance D1 from the bond pad 122 of about 50 to 400 μm. Thereduced conductivity region 130 may be formed using any of the methodsdescribed above, including implantation of ions into the p-typesemiconductor layer 116.

The light emitting device 100A may be suitable for so-called “flip chip”mounting on an underlying support. In particular, the semiconductorstructure may be mounted on a submount, bond pad or other surface withthe p-type semiconductor layer 116 facing down and the substrate 110facing up. In order to facilitate bonding the light emitting device 100Ato a support, a p-contact metal stack 118 is formed on exposed surfaceof the type semiconductor layer 116. Appropriate metal stacks for flipchip mounting of optoelectronic devices are disclosed for example inU.S. Patent Publication No. 2003/0015721 entitled “Light Emitting DiodesIncluding Modifications For Submount Bonding And Manufacturing MethodsTherefor,” the disclosure of which is incorporated herein by reference.In particular, the p-contact metal stack 118 may include an ohmic layer118A of a metal, such as platinum, that makes an ohmic contact with thep-type semiconductor layer 116. The metal stack 118 may further includea reflective layer 118B, a barrier layer 118C and/or a bonding layer118D.

The bonding layer 118D may include gold and/or tin, and may be providedto facilitate thermosonic and/or thermocompression bonding of the device100A to a submount. The reflective layer 118B may include a reflectivemetal, such as silver or aluminum, and may be provided to reflect lightaway from a submount and back into the device 100A so that it may beusefully extracted. The barrier layer 118C may include a metal, such astungsten, titanium, titanium nitride and/or nickel, that may prevent themetal of the bonding layer 118D from contaminating the ohmic metal 118Aand/or the reflector 118B. Barrier layers may be formed as described inU.S. Patent Publication No. 2005/0194603 entitled “Light Emitting DiodesIncluding Barrier Layers/Sublayers And Manufacturing Methods Therefor,”the disclosure of which is incorporated herein by reference. An optionaladhesion layer (not shown) may be provided between the barrier layer118C and the bonding layer 118D.

When an optoelectronic device, such as the device 100A shown in FIG. 5,is mounted on an opaque support member with the p-side of the device100A facing down (i.e towards the support), it may not be necessary toform a transparent electrode or a current spreading layer on the exposedsubstrate 110, since the conductivity of the substrate 110 may be highenough that current may spread naturally in the device. Accordingly, asshown in FIG. 5, the device may include a wire bond pad 122 formed onthe substrate 110. An ohmic contact (not shown) may be formed betweenthe wire bond pad 122 and the substrate 110. In some embodiments, theohmic contact may be formed in self-alignment with the bond pad 122.

The reduced conductivity region 130 may extend from a surface of thep-type semiconductor layer 116 opposite the active region 114 into thep-type semiconductor layer 116. The reduced conductivity region 130 mayextend partially and/or completely through the p-type semiconductorlayer 116. In some embodiments, including embodiments that include asubstrate 110, the reduced conductivity region 130 may extend completelythrough the active region 114 to/into the n-type semiconductor layer112. The reduced conductivity region 130 may be formed using techniquessuch as those described above with respect to FIGS. 1-4. For example,the reduced conductivity region 130 may be formed by implanting ionsinto the p-type semiconductor layer 116 through a mask, as describedabove with reference to FIG. 2A.

As further shown in FIG. 5, the reduced conductivity region 130 may begenerally aligned with the bond pad 122. Since the p-type semiconductorlayer 116 may be relatively thin compared, for example, to the substrate110, and since current may not spread readily in the p-typesemiconductor layer 116, the presence of the reduced conductivity region130 may reduce the number of photons generated in the device 100Adirectly beneath the wire bond pad 122. Accordingly, the reducedconductivity region 130 may have a shape that is about the same shape asthe wire bond pad 122. Furthermore, the reduced conductivity region 130may have an area that is about the same as, slightly less than orslightly greater than, the area of the wire bond pad 122. In someembodiments, the reduced conductivity region may have a diameter that isabout 6 to about 30 μm larger than the diameter of the bond pad 122. Inparticular, bond pad 122 may have a diameter of about 100 to 105 μm, andthe reduced conductivity region 130 may have a diameter that is about 14μm larger than the diameter of the bond pad 122. In embodimentsincluding a substrate (i.e. in which the substrate 110 has not beenremoved), it may be desirable to provide a reduced conductivity region130 that is larger in area than the bond pad 122. For example, if thewire bond pad 122 has a circular shape, the reduced conductivity region130 may also have a circular shape with an area that is less than, aboutequal to, or slightly greater than the diameter of the wire bond pad122.

Further embodiments of the invention are shown in FIGS. 6A and 6B inwhich a light emitting device 100B is shown including a p-typesemiconductor layer 116 an active region 114 and an n-type semiconductorlayer 112. A p-contact metal stack 118 is formed on a surface of thep-type semiconductor layer 116, and a wire bond pad 122 is formed on asurface of the n-type semiconductor layer 112 opposite the p-typesemiconductor layer 116. In particular, the light emitting device 100Bshown in FIGS. 6A and 6B may not include a substrate.

As further shown in FIG. 6A, a reduced conductivity region 130 isprovided in the p-type semiconductor layer 116 generally aligned withthe wire bond pad 122. The reduced conductivity region 130 may extendfrom a surface of the p-type semiconductor layer 116 opposite the activeregion 114 into the p-type semiconductor layer 116. The reducedconductivity region 130 may extend partially and/or completely throughthe p-type semiconductor layer 116. The reduced conductivity region 130may have an area that is equal to, greater than, or less than the areaof the wire bond pad 122. The reduced conductivity region 130 may belocated within the device 100B a distance D2 from the wire bond pad 122.In some embodiments, the distance D2 may be from 0.3 to 10 μm. Inparticular, the distance D2 may be about 2 to 3 μm.

FIGS. 11A-11C are plan view illustrations of a light emitting device100B including a wire bond pad 122 and an aligned reduced conductivityregion 130. As shown therein, the reduced conductivity region 130 mayhave a peripheral shape that is similar to the peripheral shape of thewire bond pad 122, which in the embodiments illustrated in FIGS. 11A-11Cis generally circular. The wire bond pad 122 and the reducedconductivity region 130 may have other peripheral shapes, such asrectangular, star, cross or other shape or combination of shapes.

As shown in FIG. 11A, the reduced conductivity region 130 may have anarea that is slightly larger than the area of the wire bond pad 122 insome embodiments, while in other embodiments the reduced conductivityregion 130 may have an area that is slightly less than (FIG. 11B) orabout equal to (FIG. 11C) the area of the wire bond pad 122.

Referring to FIG. 6B, the reduced conductivity region 130 may extendcompletely through the p-type semiconductor layer 116 and into theactive region 114. In some embodiments, including embodiments that donot include a substrate, the reduced conductivity region 130 may extendcompletely through the active region 114 to/into the n-typesemiconductor layer 112.

Further embodiments of the invention are shown in FIG. 7A, whichillustrates a light emitting device 100C that includes a p-typesemiconductor layer 116, an active region 114 and an n-typesemiconductor layer 112. A wire bond pad 122 is formed on a surface ofthe n-type semiconductor layer 112. A patterned ohmic contact 118 isformed on a surface of the p-type semiconductor layer 116 opposite then-type semiconductor layer 112. The light emitting device 100C alsoincludes a non-ohmic contact 140 on the p-type semiconductor layer 116opposite the wire bond pad 122. In some embodiments, the non-ohmiccontact 140 may include, for example, a rectifying Schottky contact. Theformation of rectifying Schottky contacts on nitride-based semiconductormaterials is well known to those skilled in the art. In otherembodiments, the non-ohmic contact 140 may include a non-conductivematerial, such as silicon dioxide.

The non-ohmic contact 140 may have a shape that is about the same as theshape of the wire bond pad 122. The contact 140 may have an area that isslightly less than, about equal to, or slightly greater than the area ofthe wire bond pad 122. Accordingly, when a voltage is applied across theterminals of the device 100C, current may not flow from the non-ohmiccontact 140 into the p-type semiconductor layer 116, which may reducethe number of photons generated in the active layer 114 beneath the wirebond pad 122.

Referring to FIG. 7B, in some embodiments, the metal stack 118 may beformed on the surface of the p-type semiconductor layer 116 in regionsother than an area of reduced conductivity 150 opposite the wire bondpad 122. That is, because the metal stack 118 is not formed in the area150, a reduced current may flow through the area 150 when the device isenergized, which may reduce the number of photons generated in theactive layer 114 beneath the wire bond pad 122.

Further embodiments of the invention are illustrated in FIG. 8. In theembodiments of FIG. 8, a device 100E includes a p-type semiconductorlayer 116, an active region 114, and an n-type semiconductor layer 112.A p-type contact 118 is formed on a surface of the p-type semiconductorlayer 116 opposite the n-type semiconductor layer 112. A wire bond pad122 is formed on a surface of the n-type semiconductor layer 112opposite the p-type semiconductor layer 116. An ohmic contact 154 isformed on the same surface of the n-type semiconductor layer 112 as thewire bond pad 122, and is electrically connected to the wire bond pad122. The ohmic contact 154 may include a transparent material that formsan ohmic contact to the n-type semiconductor layer 112, such as ITO.

A reduced conductivity region 152 is formed in the n-type semiconductorlayer 112 beneath the wire bond pad 122. The reduced conductivity region152 may extend from the surface of the n-type semiconductor layer 112 atleast partially into the n-type semiconductor layer 112. In someembodiments, the reduced conductivity region 152 may extend completelythrough the n-type semiconductor layer 112 and to/into the active region114.

FIG. 9A illustrates a device 100F according to further embodiments ofthe invention. The device 100F also includes a p-type semiconductorlayer 116, an active region 114, and an n-type semiconductor layer 112.A p-type contact 118 is formed on a surface of the p-type semiconductorlayer 116 opposite the n-type semiconductor layer 112. A wire bond pad122 is formed on a surface of the n-type semiconductor layer 112opposite the p-type semiconductor layer 116. An ohmic contact 154 isformed on the same surface of the n-type semiconductor layer 112 as thewire bond pad 122.

A first reduced conductivity region 152 is formed in the n-typesemiconductor layer 112 beneath the wire bond pad 122. The first reducedconductivity region 152 may be aligned with the wire bond pad 122 andmay extend from the surface of the n-type semiconductor layer 112 atleast partially into the n-type semiconductor layer 112. In someembodiments, the first reduced conductivity region 152 may extendcompletely through the n-type semiconductor layer 112 andto/into/through the active region 114.

A second reduced conductivity region 150 is formed in the p-typesemiconductor layer 116. The second reduced conductivity region 150 maybe aligned with the first reduced conductivity region 152 and/or thewire bond pad 122. The second reduced conductivity region 150 may extendfrom the surface of the p-type semiconductor layer 116 at leastpartially into the p-type semiconductor layer 116, and in some casesto/into/through the active region 114.

In embodiments including a reduced conductivity region 150, 152 on bothsides of the device, such as the first reduced conductivity region 152and the second reduced conductivity region 150 of the device 100F, thereduced conductivity regions 150, 152 need not be formed using the sametechniques, but could, for example, be formed using differenttechniques. For example, the first reduced conductivity region 152 couldbe formed via ion implantation, while the second reduced conductivityregion 150 could be formed using plasma treatment and or exposure tohydrogen gas, or vice-versa. Furthermore, one or both of the reducedconductivity regions 150, 152 could be formed by forming a non-ohmicmaterial on the surface of the respective semiconductor layer 116, 112prior to forming an electrical contact thereon, or by not forming theohmic contact on an area of the surface of the semiconductor layer thatcorresponds to the bond pad 122.

FIG. 9B illustrates a device 100G according to further embodiments ofthe invention. The device 100G also includes a p-type semiconductorlayer 116, an active region 114, and an n-type semiconductor layer 112.A p-type contact 118 is formed on a surface of the p-type semiconductorlayer 116 opposite the n-type semiconductor layer 112. A wire bond pad122 is formed on a surface of the n-type semiconductor layer 112opposite the p-type semiconductor layer 116. An ohmic contact 154 isformed on the same surface of the n-type semiconductor layer 112 as thewire bond pad 122.

A reduced conductivity region 152 is formed in the n-type semiconductorlayer 112 beneath the wire bond pad 122. The reduced conductivity region152 may be aligned with the wire bond pad 122 and may extend from thesurface of the n-type semiconductor layer 112 at least partially intothe n-type semiconductor layer 112. In some embodiments, the reducedconductivity region 152 may extend completely through the n-typesemiconductor layer 112 and to/into/through the active region 114.

A metal contact 118 is formed on a surface of the p-type semiconductorlayer 116 opposite the n-type semiconductor layer 112. The metal contact118 forms on ohmic contact to the p-type semiconductor layer 116 in aregion other than a reduced conductivity area of the surface of thep-type semiconductor layer 116 that is aligned with the wire bond pad122.

The light emitting device 100G also includes a non-ohmic contact 140 onthe p-type semiconductor layer 116 opposite the wire bond pad 122. Insome embodiments, the non-ohmic contact 140 may include, for example, arectifying Schottky contact. In other embodiments, the non-ohmic contact140 may include a non-conductive material, such as silicon dioxide.

The non-ohmic contact 140 may have a shape that is about the same as theshape of the wire bond pad 122. The contact 140 may have an area that isslightly less than, about equal to, or slightly greater than the area ofthe wire bond pad 122. In other embodiments, the non-ohmic contact 140may include a gap on which no contact is formed.

Still further embodiments of the invention are illustrated in FIG. 10,which illustrates a semiconductor light emitting device 100H thatincludes a reduced conductivity region 160 that extends beneath the wirebond pad 122 from a surface of the n-type semiconductor layer 112 andthrough the device 100G to the opposite surface of the p-typesemiconductor layer 116.

Some chip structures in which embodiments of the invention may beemployed are shown in isometric view in FIGS. 12 and 13. For example,FIG. 12 illustrates a chip structure 100J including a carrier substrate210, such as a silicon substrate, on which an LED structure has beenbonded via a metal bonding layer 220. A reflective layer 230 is betweenthe bonding layer 220 and the LED structure that includes a p-typesemiconductor layer 116, an active layer 114 and an n-type semiconductorlayer 112.

A pair of bond pads 122 are on the surface of the n-type semiconductorlayer 112 opposite the substrate 210. The bond pads 122 are electricallyconnected to a current spreading structure that includes a plurality ofcurrent spreading fingers 154 on the n-type semiconductor layer 112.

The reduced conductivity region 30 may be formed underneath the bondpads 122, underneath the current spreading fingers 154, and/or underboth the bond pads 122 and the current spreading fingers 154.

An exemplary horizontal chip structure 100K is illustrated in FIG. 13.The chip structure 100K includes a transparent substrate 110 on which ann-type semiconductor layer 112 is formed. A mesa structure including anactive region 114 and a p-type semiconductor layer 116 is on the n-typesemiconductor layer. A transparent ohmic contact 118, which may includeITO, is on the p-type semiconductor layer 116. A bond pad 122A is on thetransparent ohmic contact layer 118, and a current spreading finger 154Aextends from the bond pad 122A. A bond pad 122B is on the n-typesemiconductor layer 112, and a current spreading finger 154B extendsfrom the bond pad 122B. A reflective layer 23 (FIG. 1) may be providedbeneath the bond pad 122A and/or the current spreading finger 154A.

The reduced conductivity region 30 may be formed underneath the bond pad122A, underneath the current spreading fingers 154A, and/or under boththe bond pad 122A and the current spreading finger 154A.

While embodiments of the present invention are illustrated in FIGS. 1-13with reference to particular light emitting device structures, otherstructures may be provided according to some embodiments of the presentinvention. Thus, embodiments of the present invention may be provided byany light emitting structure that includes one or more of the variouscurrent blocking mechanisms as described above. For example, currentblocking mechanisms according to some embodiments of the presentinvention may be provided in conjunction with the exemplary lightemitting device structures discussed in the United States patents and/orapplications incorporated by reference above.

Embodiments of the present invention have been described with referenceto a wire bond pad 22, 122. As used herein, the term bond pad includes alight absorbing contact structure. A bond pad may be a single ormultiple layers, may be a metal and/or metal alloy and/or may be ofuniform of non-uniform composition.

Furthermore, while embodiments of the present invention have beendescribed with reference to a particular sequence of operations,variations from the described sequence may be provided while stillbenefiting from the teachings of the present invention. Thus, two ormore steps may be combined into a single step or steps performed out ofthe sequence described herein. For example, a reduced conductivityregion may be formed in a semiconductor layer before or after forming ametal layer on the semiconductor layer. Thus, embodiments of the presentinvention should not be construed as limited to the particular sequenceof operations described herein unless stated otherwise herein.

It will be understood by those having skill in the art that variousembodiments of the invention have been described individually inconnection with FIGS. 1-13. However, combinations and subcombinations ofthe embodiments of FIGS. 1-13 may be provided according to variousembodiments of the present invention. As noted above, the reducedconductivity regions 30 may be used to reduce/prevent carrierrecombination in areas of a device where generated light may be likelyto be absorbed by some feature of the device, such as a bond pad, acurrent spreading finger, a passivation region, etc. Thus, in someembodiments, the reduced conductivity regions 30 may be aligned withlight-absorbing features and/or regions of a device. However, in somecases, it may be desirable to form reduced conductivity regions 30 inother areas that are not aligned with light absorbing regions orfeatures of a device. For example, it may be desirable to providereduced conductivity regions 30 in a device that cause the device togenerate light having a desired far-field emission pattern. Thus, insome embodiments, reduced conductivity regions 30 may be used to shapethe light emission pattern of a light emitting device.

In the drawings and specification, there have been disclosed embodimentsof the invention and, although specific terms are employed, they areused in a generic and descriptive sense only and not for purposes oflimitation, the scope of the invention being set forth in the followingclaims.

1. A method of forming a light emitting device, comprising: forming ap-type semiconductor layer, an n-type semiconductor layer, and an activeregion between the n-type semiconductor layer and the p-typesemiconductor layer; forming a non-transparent feature on the n-typesemiconductor layer opposite the p-type semiconductor layer; and forminga reduced conductivity region in the p-type semiconductor layer, whereinedges of the reduced conductivity region are aligned with edges of thenon-transparent feature, the reduced conductivity region extending froma surface of the p-type semiconductor layer opposite the n-typesemiconductor layer towards the active region.
 2. The method of claim 1,wherein forming a non-transparent feature on the n-type semiconductorlayer comprises forming a wire bond pad, a current spreading fingerand/or a passivation region on the n-type semiconductor layer.
 3. Themethod of claim 1, wherein the reduced conductivity region extends fromthe surface of the p-type semiconductor layer to the active region. 4.The method of claim 1, wherein the reduced conductivity region extendsfrom the surface of the p-type semiconductor layer into the activeregion.
 5. The method of claim 1, wherein the reduced conductivityregion extends from the surface of the p-type semiconductor layerthrough the active region.
 6. The method of claim 1, wherein the reducedconductivity region extends through the active region.
 7. The method ofclaim 1, wherein the active region comprises a Group III-nitride basedactive region.
 8. The method of claim 1, wherein forming a reducedconductivity region comprises: forming a mask layer on the surface ofthe p-type semiconductor layer, the mask layer having an openingcorresponding to the bond pad region; and implanting atoms into thep-type semiconductor layer through the opening in the mask layer.
 9. Amethod of forming a light emitting device, comprising: forming a p-typesemiconductor layer, an n-type semiconductor layer, and an active regionbetween the n-type semiconductor layer and the p-type semiconductorlayer; forming a wire bond pad on the n-type semiconductor layeropposite the p-type semiconductor layer; and forming a metal contact ona surface of the p-type semiconductor layer opposite the n-typesemiconductor layer, wherein the metal contact forms an ohmic contact tothe p-type semiconductor layer in a region other than a reducedconductivity area of the surface of the p-type semiconductor layer,wherein edges of the reduced conductivity area are aligned with edges ofthe wire bond pad.
 10. The method of claim 9, further comprising forminga reduced conductivity region in the p-type semiconductor layer andaligned with the wire bond pad and the reduced conductivity area, thereduced conductivity region extending from the surface of the p-typesemiconductor layer towards the active region.
 11. The method of claim9, further comprising forming a reduced conductivity region in then-type semiconductor layer and aligned with the wire bond pad, thereduced conductivity region extending from a surface of the n-typesemiconductor layer opposite the p-type semiconductor layer towards theactive region.
 12. The method of claim 9, further comprising forming anon-ohmic contact on the surface of the p-type semiconductor layer. 13.The method of claim 12, wherein the non-ohmic contact comprises a metalthat does not form an ohmic contact with the p-type semiconductor layer.14. A method of forming a light emitting device, comprising: forming ap-type semiconductor layer, an n-type semiconductor layer, and an activeregion between the n-type semiconductor layer and the p-typesemiconductor layer; forming a wire bond pad on the n-type semiconductorlayer opposite the p-type semiconductor layer; forming a metal contacton a surface of the p-type semiconductor layer opposite the n-typesemiconductor layer, wherein the metal contact forms on ohmic contact tothe p-type semiconductor layer in a region other than a reducedconductivity area of the surface of the p-type semiconductor layer thatis aligned with the wire bond pad; and forming a reduced conductivityregion in the n-type semiconductor layer and aligned with the wire bondpad, the reduced conductivity region extending from a surface of then-type semiconductor layer opposite the p-type semiconductor layertowards the active region, wherein the non-ohmic contact comprises aninsulator on the surface of the p-type semiconductor layer.